A wireless access system conventionally supports an idle mode to reduce power consumption by a mobile station (MS). In idle mode, the MS is not yet registered to a specific base station (BS) and also is not handed over from one BS to another BS in a paging zone. A paging zone is composed of a plurality of BS areas. The MS receives a predetermined paging message (e.g., MOB-PAG-ADV) to enable the MS to periodically recognize the presence or absence of downlink traffic destined for the MS. Such operation may reduce power consumption by the MS.
Idle mode operation is described below. In a paging zone is a plurality of BSs contained in a group, called a paging group. The BSs included in the same paging group have the same paging cycle (e.g., Paging_Cycle) and the same paging offset (e.g., Paging_Offset). The MS may request the BS to enter an idle mode. The BS transmits its paging group ID (e.g., Paging Group ID), a paging cycle corresponding to the paging group ID, and a paging offset to the MS to enable the MS to enter the idle mode. In such case, the MS and the BS operate a timer for updating position information related to the MS that entered the idle mode.
During the idle mode, the MS receives the paging advertisement message (e.g., MOB-PAG-ADV) configured as broadcast information from the BS at intervals of a predetermined paging time. The MS may determine whether to continuously maintain the idle mode, to terminate the idle mode, or to perform a location update procedure using the received paging advertisement message (e.g., MOB-PAG-ADV). If uplink traffic is to be transferred from the MS during the idle mode, the MS may terminate the idle mode.
If downlink traffic is to be received by the MS during idle mode, the BS may allow the MS to terminate the idle mode using the paging advertisement message (e.g., MOB-PAG-ADV). If the MS in the idle mode loses a synchronization point such that it does not receive the paging advertisement message (e.g., MOB-PAG-ADV) by a set time, the MS terminates the idle mode.
If the MS in the idle mode moves from a current paging group to another paging group, or if a timer for updating position information expires, invalid parameters are updated according to a network re-registration procedure such that a location update procedure is performed. In such case, the MS does not perform removable procedures according to management resource information managed by the BS so that the MS may perform the location update procedure.